Battery Charging Hell

[guy99]

Need help with battery management.

We're camped on BLM land in Quartzsite, relying on the generator to charge the batteries when needed. But even running the generator 8 hours per day, the batteries is still being drawn down. Here's what I have:

I have 1984 Airstream 310 Limited Motorhome with

4 Costco group 27 marine deep cycle batteries rated at 115 amp hours (new in November).
A 200 amp alternator
A Honda EV6010 6000 watt generator
A WFCO Model 9865 - 65 amps converter

The WFCO converter won't go into boost mode (14.4 Volts) unless the batteries are AT LEAST 50% discharged, per WFCO tech support so all of the battery charging is occurring at 13.2 to 13.6 volts.

I think this is my problem - my converter really can't do what I need it to do.

Am I correct?

[87MH]

With the batteries and charging systems you have I would suspect a parasitic draw.

I think it is time to purchase an Ampmeter that will indicate a range of ampere drawdown (1 to 10, and 10 to 100?) and find out just what device is drawing down the batteries - could be the electric steps, the air compressor, or the battery isolator?

Also, 13.2 volts is not all that low -

[Fyrzowt]

It sounds like you're relying on the converter to charge the batteries. Do you have a battery charger that you can use instead? That should give you better results.

[guy99]

Originally Posted by 87MH

With the batteries and charging systems you have I would suspect a parasitic draw.

I think it is time to purchase an Ampmeter that will indicate a range of ampere drawdown (1 to 10, and 10 to 100?) and find out just what device is drawing down the batteries - could be the electric steps, the air compressor, or the battery isolator?

Also, 13.2 volts is not all that low -

I have a Trimetric 2020 which tells me lots of stuff like the instantaneous load, the net drawn down in amp-hours, voltage, etc.

I have 460 amp-hours of battery capacity. My basal drawn is .8-.5 amps. Other draws are lights, fans, tv, computer, water pump, etc. We use about 50-75 amp-hours in a 24 hour period. I'm trying to replace those amp hours by running the generator.

[RUSSELL]

I do not understand. Why when you run your generator you discharge your batteries. When you are on shore power or generator you schould use the battery very little. It may be that your invertor does not see the 120v from generator and continues to convert 12v to 120v. There schould be a relay in it to swich out when not needed.
Russ in sunny and cool Tucson Az.

[guy99]

Originally Posted by Fyrzowt

It sounds like you're relying on the converter to charge the batteries. Do you have a battery charger that you can use instead? That should give you better results.

I'm confused. I thought that was what my three stage 65 amp converter was for. How big a battery charger would I need and why would it be better?

[guy99]

Originally Posted by RUSSELL

I do not understand. Why when you run your generator you discharge your batteries. When you are on shore power or generator you schould use the battery very little. It may be that your invertor does not see the 120v from generator and continues to convert 12v to 120v. There schould be a relay in it to swich out when not needed.
Russ in sunny and cool Tucson Az.

My batteries are not discharging when the generator is running. They are actually being charged, but very slowly.

[Goin camping]

Guy, I'm no expert but it seems that your "in house" system is not charging the batteries. Thus hooking your genny directly to the batts via a battery charger would bypass the defective part and recharge your batts.

If you go that route you could either buy four battery chargers and charge em up real fast or buy one and charge slower. Not being real smart in electrical I'd go buy four battery chargers. IMHO.

[rseagle]

Guy99,

You're batteries are probably heavily sulfated due to the frequent charging and discharging. I'd recommend at Power Pulse desulfator by Pulse Tech. See link for a retailer.

Battery Desulfators @ Survival Unlimited .com -

I'm going onto my 7th season with same battery since I use this desulfator. They really help. A 4th Phase charge wizard attached to your WFCO will also do the same thing.

[guy99]

Originally Posted by rseagle

Guy99,

You're batteries are probably heavily sulfated due to the frequent charging and discharging. I'd recommend at Power Pulse desulfator by Pulse Tech. See link for a retailer.

Battery Desulfators @ Survival Unlimited .com -

I'm going onto my 7th season with same battery since I use this desulfator. They really help. A 4th Phase charge wizard attached to your WFCO will also do the same thing.

Batteries were purchased in November 2007. I have this device installed: Onboard Desulfator. So they really shouldn't be sulfated.

[alan]

Remove and clean all of your battery connections. I had one work slightly loose one a trip last summer which messed up the ability of the converter to charge the batteries.

[guy99]

Originally Posted by alan

Remove and clean all of your battery connections. I had one work slightly loose one a trip last summer which messed up the ability of the converter to charge the batteries.

Good suggestion, but, I put in new cabling in late November as we were heading out on the current trip. I have had all the connection apart in the last two days. They are all clean and tight.

[garry]

There is the posibility you have one bad battery in the bunch that is causing the problem. I would pull all the batteries and load test them individualy.

Most auto stores have load testers if you don't have one.

Garry

[SilvrSausage]

13.2 volts is a weak charging voltage. In automotive applications, we look for 13.5 to 14.5 volts as the acceptable ballpark. Less, and you will have battery issues. The converter is perhaps optimized for ground hookups rather than a generator you have to run. Therefore, it is probably conservative about charging voltage, to avoid overcharging when always connected. An automotive charger of adequate capacity will be able to charge all four batteries at once.

What is the amperage that the charger is producing? How much does EACH battery draw?

Try measuring the voltage at the converter itself. If it is more than say 2/10 volt higher than at the batteries, start testing for voltage drop in the positive and negative circuits. Tightening all the connectors addressed the number one cause, though.

I'll bet there are trim pots you could adjust inside the converter to change the threshhold voltages for the various charging states. If you feel you know what you're doing, and don't care about the warranty, try playing with those.

Garry's idea was good, test each battery. Try to have them fully charged first, even with one of the modern conductance testers.

Four batteries should have adequate capacity! Still, are you running LED lights at all? Incandescents are battery hogs. Also, aside from parasitic draws, a malfunctioning appliance could be the culprit, such as a heater fan motor with dry bushings; it might draw more than twice its rated amperage without blowing fuses.

Good luck.

[Wabbiteer]

You don't mention adding water - have they been thirsty?

You also only mention what the charger is doing - the batteries are boss, what are the before and after readings w/ converter off & for what period of time has it ran?

One can not expect greater than +/- 10% accuracy to calculate the charged state with a voltmeter unless your lead-acid batteries have rested at least 4 hours (nothing in/out) - even after 4 hours the error margin is still +/- 3-5%. You need to record temperature compensated specific gravity measurements over several entire charge-discharge cycles to have more than a guess at the battery state at any point of time. The trimetric gauge will happily throw readings out but without knowing what the chemistry of the battery is doing compared to the SG readings there is still a possible rate of error built in.

Your generator is most efficient with about a 80% load on it but the load of your converter at full power draws 1260 watts so the pain threshold of running that beautiful 12.2 HP Twin Cylinder OHC Four-Stroke Liquid-Cooled 359 cc generator rises just on that point. For the 1260 watts maximum input of the WFCO 65A converter you get ~1000 watts energy into the batteries on top charge rate (14.2V x 65A) so there is another 20% losses before you start calculating your battery loads.

Deep cycle batteries across their charge range lose another average 8% charging and 8% supplying power to that is another 15% loss in order to have shore power disconnected. Then there is the wiring losses of 12V which are additive to whatever device loads are - good engineering will place it no greater than 5%; so adding device loads together you need to add 20% to get needed amp-hours to replace battery usage.

Since it sounds like you are full-timing you would be wise to ignore the WFCO stages and use the Bulk, Finishing, and Equalization charge scheme that is the historic standard. Get Costco to share with you the battery manufacturer's name and go get online charge recommendations for their chemistry and find a charger that will allow you to tune the set points between bulk and finishing charge.

Just the losses of the converter alone would get me thinking of using an inverter-charger, a used trace 2500w modified sine wave inverter with 120 amp charge circuit is on eBay at the moment that scrounges every bit of 120V input into the batteries, but this would be as a dedicated charger with the bonus of having 120VAC output...

[guy99]

Originally Posted by garry

There is the posibility you have one bad battery in the bunch that is causing the problem. I would pull all the batteries and load test them individualy.

Most auto stores have load testers if you don't have one.

Garry

My thinking exactly so I bought a 100 amp load tester and tested each battery individually. They all tested good.

I also measured the specific gravity of each cell, they were consistent and on the border line between white and red.

So, that doesn't explain anything.

[garry]

Well your orignal question was about the converter and IMO the converter should have no problem bringing the batteries back to full charge in just a few hours unless fully discharged. Since all the batteries test good I would say the converter is not doing it's job. From what you posted earlier the bulk charge should kick in around 12.10 to 12.06 VDC can you test for this with a digital meter?
As others have suggested you can use a stand alone battery charger to bring everything up to a full charge but to have to do this on a fulltime basis is a work around.

Garry

[TitusLivy]

I'd begin by simplifying the problem:

(1) Reduce the load on the batteries to zero [or as close as practical];
(2) measure the voltage across the batteries;
(3) recharge the batteries;
(4) after 1-hr, 2-hrs [etc] stop charging and measure the voltage across the batteries.
(5) Use the table posted by others to calculate the "state of charge" based on the battery voltage observed after each interval.

I think the rate at which the batteries are charging will provide helpful clues.

You will presumably observe that the batteries are not charging as rapidly as expected. In that case, I'd break the problem down further by examining the various subsystems: generator, converter, batteries. For example, you may be able to beg, borrow, steal...(No! I guess you've got enough problems already)...beg, borrow, or rent a battery charger you could use to charge the batteries directly. If they still charge slowly, I'd focus my attention on them, since they would appear to be the problem. On the other hand, if they charge correctly, then it's time to focus on the other subsystems: converter & generator.

Hope this suggestion is useful.

Titus

[Wabbiteer]

Wow - for someone who quotes the Dali Lama in their signature you are quite the all-purpose bully! It took me close to an hour to research and compose my first response but here you are again expecting pre cognizance and someone tell you what you want to hear...

"...consistent and on the border line between white and red... So, that doesn't explain anything." HUH? thats not a measurement! (resembles a 'my car is red & white, what size tires do I need' answer!)

For specific gravity a reading of 1.270 is fully charged, if you are serious with ensuring your batteries last you need to invest in a precision meter - well, maybe not, but you did evade two outright diagnostic questions asked among the others asked of you in these posts. Imagine that, someone asking details! Dialoug is give and take...

To better follow the "taa la’i bla ma", apologies if you felt uncomfortable...

Lets look at the problem again from a new perspective. You have 240+ pounds of batteries - It is January, and you have had some problems since Novemeber. If the batteries are not in a conditioned atmosphere (75°F is ideal) you need temperature compensated charging, even 20°F lower you need to boost voltage by almost 2/10ths volt (27mV/°C is common) to make up for the lowered activity; otherwise your charger will run and run and never bring the SOC (state of charge) up to even 90%...

Your charger puts out ~1000 watts of energy and if you lose 10% charging current due to resistance heating it would take close to two hours charging to raise battery string core temperature 1 degree celcius - so don't count on charging to help keep battery temperatures up since it IS shedding the heat almost as fast....

Suggested reading - The 12volt Side of Life (Part 1) not to be taken as gospel; but should help you make better educated observations... living with 12 volts. (I knew I'd seen 87MH's chart somewhere before, but many charts are 2/10ths of a volt higher on all points so following that one could be very hard on batteries!!)

And another source of charge wizardry

"a rough estimate of the actual SOC"

% of Charge - - - - - - Charging - - - - - - - At Rest - - - - Discharging

100 - - - - - - - - - - - - 14.75 - - - - - - - - 12.70 - - - - - - 12.50
90 - - - - - - - - - - - - - 13.75 - - - - - - - - 12.58 - - - - - - 12.40
80 - - - - - - - - - - - - - 13.45 - - - - - - - - 12.46 - - - - - - 12.30
70 - - - - - - - - - - - - - 13.30 - - - - - - - - 12.36 - - - - - - 12.25
60 - - - - - - - - - - - - - 13.20 - - - - - - - - 12.28 - - - - - - 12.15
50 - - - - - - - - - - - - - 13.10 - - - - - - - - 12.20 - - - - - - 12.00
40 - - - - - - - - - - - - - 12.95 - - - - - - - - 12.12 - - - - - - 11.90
30 - - - - - - - - - - - - - 12.75 - - - - - - - - 12.02 - - - - - - 11.70
20 - - - - - - - - - - - - - 12.55 - - - - - - - - 11.88 - - - - - - 11.50
10 - - - - - - - - - - - - - 12.25 - - - - - - - - 11.72 - - - - - - 11.25

Source: Photovoltaic systems and renewable energy: Measuring Battery State of Charge

[Buttercup]

Well, I may be coming in late on this thread but I have one question... The batteries were new in November, 2007. How have they been charged after that? In many cases "fresh" batteries need to be deeply charged AND discharged a few time to get them to peak performance.
It is sort of like muscles - they work but work better when exercised a little.
Also, a deep 14.5 volt charge is really what is needed to get it really pumped up. However some chargers will not go to that level of charge unless the battery has had no draw for at least 24 hours, at least I believe that is the case with my Intellipower.
It sounds like your charger is underperforming for you while trying to charge newer batteries and that this combination may be the bigger part of your situation.
I am following this thread so I do hope you keep us informed as to what you find.